1. Definition of Terms
A) Internal combustion engines: in general refers to engines that naturally aspirate with a throttle valve controlling and restricting the air flow through the intake manifold and where fuel does not partake in a lubricant function.
B) Any fuel delivery system, for example, carburetor, throttle body injection continuous injection system, multipoint injection, pulsed electronic fuel injection, mixer dosifier of air for natural gas or liquid petroleum gas, diesel direct injection.
C) Any fuel: refers mainly to fuels inflammable by a spark of ignition, such as: gasoline, methanol, ethanol, or gasohol mixtures, natural gas, liquid petroleum gas. In case of any reference to diesel or fuel-oil, we will refer specifically to them.
2. Background Discussion
It is common knowledge that for a conventional combustion engine, the ideal combustion could be defined by the relation between: the maximum amount of energy generated by the minimum amount of fuel mixed with the exact amount of oxygen present in the air-fuel mixture, uniformly distributed in each cylinder to produce the total burning of fuel, while a minimum production of solid residues and polluting emission results. This definition would represent reaching almost 100% efficiency in a combustion process. For the purpose of reaching maximum efficiency and a significant reduction of fuel consumed by internal combustion engines, it is convenient to discriminate the main factors involved in the combustion process as well as the problems and limitations of operational design inherent to engines and how it affects their internal combustion and performance.
3. Oxygen, Essential Factor
In order to burn fuel and for combustion to take place, it is necessary for a carburetant to be present. Specifically, the carburetant is oxygen, which is an indispensable element for enabling combustion to take place. Combustion is an oxidation process where the elements carbon and hydrogen present in the oxidation reaction provide high energy production and harmless byproducts (carbon dioxide and water).
Rich Condition--if we work with an excess of fuel and there is not enough oxygen to burn all the fuel, it will result in certain portions of uncombusted fuel, which will form carbon deposits in the combustion chamber and highly toxic emissions such as residual hydrocarbons and carbon monoxide expelled to the environment through the exhaust system. Also, engines will consume a greater amount of inefficient fuel wasted in producing harmful byproducts and not in generating energy.
Lean Condition--Due to the fact that all the oxygen used in internal combustion engines is supplied by atmospheric air with the inconvenience that air can only supply approximately 20% of oxygen together with an unwanted 80% of nitrogen, it would be reasonable to supply excess of air to burn all the fuel entering the combustion chamber. But, the problem is that excess air generates high combustion temperatures and both elements nitrogen and oxygen combine, thereby forming nitrogen oxides (NOx emissions) which are harmful byproducts, key element of smog. Both working conditions (rich and lean) produce harmful emissions contributing to smog formation, in contrast to the clean air desired.
Stoichiometric Ratio
For today's engines, with the increased emphasis on fuel economy and reduced emissions, the air-fuel ratio has to be controlled much more carefully. The ideal air-fuel ratio, the one which yields the most complete combustion and the best compromise between rich and lean mixtures is 14.7:1, the mixture is neither rich nor lean, this ratio is expressed in terms of mass. Modern technologies and vehicle manufacturers express that the stoichiometric ratio can also be described in terms of the air requirements of engines, and calls this, the `EXCESS AIR FACTOR` or LAMBDA. At the Stoichiometric Ratio, when the amount of air equals the amount required for complete combustion of fuel and there is no EXCESS AIR-Lambda=1. When there is excess air (air-fuel ratio leaner than stoichiometric) Lambda will be greater than one. When there is a shortage of air (air-fuel ratio richer than stoichiometric) then Lambda will be less than one. This concept of Lambda (the excess air factor) was created to support thinking in terms of the air requirements of engines working with electronic fuel injection where intake air-mass flow is measured and a computer determines the corresponding amount of fuel to be injected. Older carburetor systems tend to run richer than the ideal air-fuel ratio, where air flow through carburetors extracts proportional amounts of fuel from venturis. In other words, every time the term "Air" appears in this application, it should be understood, which way and how much oxygen is supplied to the engine and possible harmful byproducts affecting emissions.
Limitations of the Operational Design
This concerns, restrictions and inconveniences related to engine design that affect negatively the appropriate supply of "Air" for the combustion process promoting incomplete combustion and affecting regulated emissions. Main Limitation--It is well known that in carbureted and throttle body injected (Central Injection) engines, the fuel and the air, are supplied together by the fuel delivery system, where the vacuum low pressure is responsible for the aspiration and formation of an air flow drawn from the ambient (at atmospheric pressure), This intake air flow will receive the intake atomized fuel (from venturis or fuel injectors) in order to transport it, mixed in the air current running through the intake manifold for its later ignition at the combustion chamber. In multipoint fuel injection (Ported Injection) fuel is sprayed by injectors at ports located into the intake manifold very near to the intake valves. For both cases, older and latest fuel delivery systems, the main limitation is the throttle valve controls that restrict the unique air supply. This joint supply of fuel and restricted air creates an inconvenient interdependence between them, which in the end translates into limitations imputable not only to the design, but also to the way the engine performs and the way the fuel delivery system operates under different throttle positions and vacuum variables, generating problems such as: defective vaporization and adherence of liquid fuel to elbows, walls, and ports of the intake manifold; irregular distribution of air-fuel mixture to each of cylinders; rich or lean mixtures under different operational conditions. All these problems translate into partial burning of fuel resulting in certain portions of uncombusted fuel wasted in producing harmful byproducts. Furthermore, for carbureted engines it is impossible to increase the air flow, taken in through the fuel delivery system, without producing simultaneously extraction and aspiration of an additional amount of fuel. Consequently, this explains the inconvenient interdependence resulting from a joint supply of air and fuel, as well as removing the possibility of supplying additional air by restricted normal intake. On the other hand, in order to reduce the fuel consumption, obviously the amount of fuel delivered should be reduced. To manage this, we must reduce the diameter of the passages located at internal parts (gillets, venturis, or injectors), through which the fuel runs in the fut. I delivery system, or shorten the pulse time (Electronic Injection). Such a reduction could be so noticeable, that it would be very easy to find the proper amount of restricted air to match and carry out the combustion of all the reduced amount of fuel, with a minimum production of residues and effluents, but also, energy excepted by explosion will be reduced, thus generating less power. From the above we can derive that a reduction of fuel `per se`, implies a sacrifice in the power of the engine. Such problems and limitations just mentioned are subject to corrections and improvements, this is one of the objectives of this invention.
4. Brief Summary of Prior Art
During several years, numerous efforts have been made focused mainly in developing methods to reduce gasoline consumption, while improving efficiency of combustion and at the same time, reducing the exhaust emissions and fumes expelled-to the environment. A great number of new techniques and a diversity of inventions have been implemented and developed, in order to correct certain deficiencies of carbureted and central injected engines, such as: incomplete vaporization of gasoline, air-fuel mixtures for different driving conditions, irregular distribution of fuel in the cylinders, lack of air during acceleration or oxygen insufficiency. In order to overcome these deficiencies, various devices have been developed to generate micro-turbulences with air at sonic speeds, vaporized hot air, air injection controlled by: diaphragms, valves, pistons, or passages with narrow opening and small orifices. Other methods and devices inject pure oxygen alone or mixed with air. After having analyzed each of these systems and devices in detail, it is possible to observe that none of them have been designed to reduce the a mount of fuel `per se` entering the combustion chamber. Nevertheless, we can observe that they allow the entrance of previously filtered air in some cases at intervals and in other cases in a continuous pattern, while in yet other cases the ambient air is introduced using pressure. Most of these are connected below the fuel delivery system, either through the P.C.V. valve or directly to the intake manifold. But, all of them impose limitations and restrictions by blocking the running of the necessary volume of additional air.
To understand the restrictive supply of air through devices, it would be convenient to explain the meaning of vacuum in terms of Absolute Pressure. The manifold vacuum is currently specified in inches of Mercury (In. Hg). "29.92 in. Hg" is the difference between standard atmospheric pressure at sea level and absolute vacuum. Using Atmospheric pressure as a baseline zero, any lower manifold pressure is expressed as a negative value-vacuum implying a strong, sudden pull of air. On the other hand, using Absolute Pressure as a reference point, the piston on its intake stroke is creating a very low pressure in the cylinder approaching zero Absolute Pressure, or Maximum Absolute Vacuum. Outside the engine, atmospheric pressure is always a positive value, and it is continuously pressing over the throttle valve which separates both opposite pressures and regulates the intake air flow. Incoming air is matched with fuel to produce power and an increase in r.p.m. replacing the lost vacuum, by this form the engine works in a compensated way. The undiscriminated supply of additional air through an alternate way (devices), would produce a drastic reduction of negative pressure of vacuum (Low Absolute Pressure), by its abrupt annulment with the positive atmospheric pressure (High Absolute Pressure) causing sudden compensation (the quick equalizing) of both pressures without raising the r.p.m., provoking failures and disfunction of the engine until it is turned off.
Advanced Technologies. Government standards for emissions and fuel economy are becoming increasingly important to save fuel and clean air, and to preserve the global environment. During the past three decades, car makers have been continuously working to meet mandated fuel economy standards and tighter emission limits for the 90's. Computerized engine control and fuel injection are the only way to meet those needs. In contrast with carburetors, the throttle valve regulates (restriction) only air flows into the engine, and fuel injection systems deliver fuel by forcing it into the incoming air stream. Incoming air is measured by air flow or air mass sensors, signals received by computer determine the fuel to be delivered in precise amounts based directly on that measure. Multipoint systems delivers fuel at the engine intake ports near the intake valves. This means that the intake manifold delivers only air, in contrast to carburetors or single-point (Central) fuel injection systems in which the intake manifold carries the air-fuel mixture. As a result, these systems offer the following advantages: (1) Reduced air-fuel ratio variability; (2) Fuel delivery matched to specific operating requirements; (3) Improved driveability by reducing the throttle change lag which occurs while the fuel travels from the carburetor or throttle body to intake ports; (4) Increased fuel economy by avoiding condensation of liquid fuel on interior walls of the intake manifold (manifold wetting); (5) Engine run-on is eliminated when the key is turned off. Additionaliy, the exhaust oxygen sensor (Lambda sensor) and the control module (Computer) form the air-fuel ratio closed-loop system that continually adjusts the mixture by changing the fuel-injector pulse time. In normal warm operation the oxygen sensor generates a higher voltage because the mixture is rich, so the control module reduces pulse time to make the mixture lean. Oxygen sensor voltage falls, so the control module increases pulse time to enrich the mixture. Closed-loop air-fuel ratio control operates quickly and continuously to maintain the air-fuel ratio as close as possible to the stoichiometric, because this control cannot hold the air-fuel mixture within the required range. Successful operation of a three-way catalytic converter requires that the air-fuel ratio be maintained at Lambda=1. At this point the emissions of all three pollutants (NOx, CO and residual HC) is reduced to the lowest level. Because of tightening exhaust emissions regulations and the need for a three way catalyst, a Lambda sensor (exhaust gas oxygen sensor) is provided on virtually every car made since 1981, domestic or import, fuel injected or carbureted. Catalytic converters control emissions and reduce the need for engine tuning. In addition, government legislation established an average miles per gallon (mpg) standard to apply to the total fleet of cars each manufacturer delivers each year. Further, the target mpg standard rose each year, starting al 18 mpg in 1978, and rising up to 27.5 mpg in the 1990's. The obvious question: What is the reason? Harmful emissions under partial combustion control have been discussed above. NOx controlled harmless emissions and carbon dioxide (CO2-greenhouse effect) emission will be discussed below. Until recently, carbon dioxide (CO2) was considered a harmless emission. But now the greenhouse effect must be considered. Recent studies show that CO2 is accumulating in the upper atmosphere, trapping global heat much as glass traps heat in a greenhouse. Most experts consider that global warming of only a few degrees would have disastrous worldwide results.
The probable results are a rise in global temperatures, successive heat waves, and iceberg melting, which would raise Ocean levels to flood seaside properties worldwide. Any burning of fossil fuel (even properly combusted) produces carbon dioxide. About 750 cu. ft. of invisible CO.sub.2 (twice the volume of a typical car) are expelled through exhaust systems for each gallon of fuel burned. Unlike the other combustion by-products (HC,CO,NOx), the CO.sub.2 cannot be treated to eliminate its harmful effects. Reduction in CO.sub.2 requires reducing the amount of fuel burned. It is an object of this invention to improve efficiency to its `optimal level`.
The provision of a nonrestrictive device that allows entry of additional air, via the intake manifold, avoiding the internal decompensation of the engine, but that at the same time allows a `per se` fuel-CO2 reduction, without a loss of power, is another principal objective of this invention.